Conventional locating techniques include techniques using a base station of a mobile communication network, techniques using a Global Positioning System (GPS) receiver, and techniques using Radio Frequency Identification (RFID) information.
The locating techniques using a base station of a mobile communication network include the technique of locating a user using identification information of a base station to which a user terminal belongs and the technique of calculating the position of a user terminal using the arrival time and difference in angle of a frequency transmitted to the user terminal from three adjacent base stations.
Typically, a conventional position information providing system gathers position information of user terminals in a server providing position information, and provides a variety of additional services by using current position information of the user terminals gathered in the position information server.
The technique of locating using a base station or using a GPS receiver brings about the problems of signal attenuation, multiple paths, etc. in civic center regions where buildings are dense or in shadow regions, and thus causes the problem that position information cannot be precisely gathered.
Further, in case that position information is stored in a server, individual users have to receive their position information from the server through a radio communication link. Due to this, the users have to pay communication costs in order to receive position information.
Meanwhile, the technique of providing position information using RFID can be largely classified into the Real-Time Locating System (RTLS) technique and the technique of directly using positions held by RFID tags. The RTLS technique is a technique that utilizes RFID tags and an RFID reader. That is, the server calculates the position of the RFID reader by using a time difference or the like in communication between the RFID reader and the RFID tags. However, this RTLS technique has the problem to be solved in order to be applied to a vehicle traveling at a high speed.
Moreover, the technique of directly providing position information held by RFID tags through an RFID reader is a technique in which position information held by the RFID tags is received under the situation in which the RFID reader is installed in an object in advance, so that the position information can be utilized in the object. However, this technique has a lot of problems to be solved in order to be applied to a vehicle traveling at a high speed although it is able to provide real-time position information to a stationary object.